In the distribution of electrical energy, electric utility companies have typically found it desirable to measure not only real load energy as watthours delivered to a user, but also, reactive load quadergy as varhours (or reactive volt-ampere hours), apparent energy and power factor. By measuring both watthours and varhours, electric utilities can more accurately apportion the costs of supplying energy to customers having varying demands and loads.
Furthermore, because the capacity of the distribution network for delivering electrical energy to consumers is a function of the apparent energy as volt-ampere-hours and not just the real or reactive components thereof, electric utility companies typically desired that electrical energy meters simultaneously maintain time-based records of apparent energy, power factor and other "derived" load profile metering quantities, in addition to watthour and varhour usage.
These records are typically generated internal to the meter, at the periodic completion of consecutive load profile time intervals. An example of a meter with record keeping capability is the Phase 3i.TM. Electronic Meter with KRC-901.TM. Recording Register, which is publicly available from General Electric Company, Somersworth, N.H. Dedicated recording registers having up to 32K bytes of memory for retaining multiple channels of load profile data are also publicly available. For example, the General Electric TMR-900i.TM. Recording Register can compile up to fifty-four (54) days of data at five (5) minute intervals.
The amount of internal memory needed to record interval data is a function of the product of the number of channels and the number of intervals being recorded and the number of required data bytes per channel. Accordingly, the memory requirements can become exorbitant as the number of channels increases and/or the number of intervals increases. These large memory requirements can also increase the cost of the meter or dedicated recording register. Thus, notwithstanding the fact that the above described meters and dedicated recorders are capable of accumulating load profile data for a plurality of channels and for extended periods of time, there continues to be a need for a multi-channel load profile recorder which reduces the amount of memory space needed for the retaining electrical energy metering quantities, so that additional channels and intervals can be recorded.